Journal article
Highly Structured Slow Solar Wind Emerging From an Equatorial Coronal Hole
Nature (London), Vol.576(7786), pp.237-242
12/12/2019
DOI: 10.1038/s41586-019-1818-7
PMID: 31802007
Abstract
At solar minimum, the solar wind is observed at high solar latitudes as a predominantly fast (> 500 km/s), highly Alfvenic, rarefied stream of plasma originating deep within coronal holes, while near the ecliptic plane it is interspersed with a more variable slow (< 500 kms) wind. The precise origins of the slow wind streams are less certain, with theories and observations supporting sources from the tips of helmet streamers, interchange reconnection near coronal hole boundaries, and origins within coronal holes with highly diverging magnetic fields. The heating mechanism required to drive the solar wind is also an open question and candidate mechanisms include Alfven wave turbulence, heating by reconnection in nanoflares, ion cyclotron wave heating and acceleration by thermal gradients1. At 1 au, the wind is mixed and evolved and much of the diagnostic structure of these sources and processes has been lost. Here we present new measurements from Parker Solar Probe at 36 to 54 solar radii that show clear evidence of slow, Alfvenic solar wind emerging from a small equatorial coronal hole. The measured magnetic field exhibits patches of large, intermittent reversals associated with jets of plasma and enhanced Poynting flux and interspersed in a smoother and less turbulent flow with near-radial magnetic field. Furthermore, plasma wave measurements suggest electron and ion velocity-space micro-instabilities that have been identified with plasma heating and thermalization processes. Our measurements suggest an impulsive mechanism associated with solar wind energization and a heating role for micro-instabilities and provide strong evidence for low latitude coronal holes as a significant contribution to the source of the slow solar wind.
Details
- Title: Subtitle
- Highly Structured Slow Solar Wind Emerging From an Equatorial Coronal Hole
- Creators
- S D Bale - University of California, BerkeleyS T Badman - University of California, BerkeleyJ W Bonnell - University of California, BerkeleyT A Bowen - University of California, BerkeleyD Burgess - Queen Mary University of LondonA W Case - Smithsonian Astrophysical ObservatoryC A Cattell - University of MinnesotaB D G Chandran - University of New HampshireC C Chaston - University of California, BerkeleyC H K Chen - Queen Mary University of LondonJ. F. Drake - Joint Space Science InstituteT Dudok de Wit - Centre National de la Recherche ScientifiqueJ P Eastwood - Imperial College LondonR E Ergun - Laboratory for Atmospheric and Space PhysicsW M Farrell - Goddard Space Flight CenterC Fong - University of California, BerkeleyK Goetz - University of MinnesotaM Goldstein - Goddard Space Flight CenterK A Goodrich - University of California, BerkeleyP R Harvey - University of California, BerkeleyT S Horbury - Imperial College LondonG G Howes - University of IowaJ C Kasper - University of MichiganP J Kellogg - University of MinnesotaJ A Klimchuk - HeliophysicsK E Korreck - Smithsonian Astrophysical ObservatoryV V Krasnoselskikh - Université d'OrléansS Krucker - University of California, BerkeleyR Laker - Imperial College LondonD E Larson - University of California, BerkeleyR J MacDowall - Goddard Space Flight CenterM Maksimovic - Observatoire de ParisD M Malaspina - Laboratory for Atmospheric and Space PhysicsJ Martinez-Oliveros - University of California, BerkeleyD J McComas - Princeton UniversityN Meyer-Vernet - Observatoire de ParisM Moncuquet - Université Paris Sciences et LettresF S Mozer - University of California, BerkeleyT D Phan - University of California, BerkeleyM Pulupa - University of California, BerkeleyC Salem - University of California, BerkeleyD Stansby - Imperial College LondonM Stevens - Smithsonian Astrophysical ObservatoryA Szabo - HeliophysicsM Velli - Planetary Science InstituteT Woolley - Imperial College LondonJ R Wygant - University of Minnesota
- Resource Type
- Journal article
- Publication Details
- Nature (London), Vol.576(7786), pp.237-242
- DOI
- 10.1038/s41586-019-1818-7
- PMID
- 31802007
- NLM abbreviation
- Nature
- ISSN
- 0028-0836
- eISSN
- 1476-4687
- Publisher
- Nature Research
- Language
- English
- Date published
- 12/12/2019
- Description audience
- PUBLIC
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428789002771
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